The present invention relates to fluid pumps and pertains particularly to method and apparatus for pumping fragile articles.
Rotary disc pumps have been known for a considerable length of time. These pumps, however, have not gained widespread use because they have been unable in the past to compete effectively with positive displacement pumps and bladed impeller pumps for the pumping of fluids.
The prior art of which applicant is aware indicates that such pumps have been proposed as early as 1913, with minor improvements being made through the years until the present time. The prior art is exemplified, for example, by the following prior art patents:
U.S. Pat. No. 1,061,142, issued May 16, 1913 to N. Tesla. PA1 U.S. Pat. No. 2,087,834, issued July 20, 1937 to Brown et al. PA1 U.S. Pat. No. 3,487,784, issued Jan. 6, 1970 to Rafferty et al. PA1 U.S. Pat. No. 3,644,051, issued Feb. 22, 1972 to Schapiro. PA1 U.S. Pat. No. 4,025,225, issued May 24, 1977 to Durant.
Other patents of interest include British Specification No. 179,043, dated May 4, 1922 to N. Tesla, and
French Patent Specification No. 866,706, issued May 31, 1941 to Girodin.
These pumps are all based on the theory that the friction of the fluid on the surfaces of the plates of the rotor during rotation of the rotor develops a centrifugal force propelling the fluid out toward the periphery of the plates. These all, however, maintain and recognize the necessity for maintaining a fairly close tolerance of the spacing between the discs. There has long existed a need for systems for conveying fragile articles rapidly and conveniently without damage thereto. Fruits and vegetables, for example, are currently conveyed by means of screw-type conveyors when it is essential to convey them without a fluid medium. Prior to the present invention, there has been no known technique for conveying such articles by means of a pump in a fluid medium without damage thereto. Currently, some pumps are used to unload some fish from fishing vessels into processing tanks or the like at canneries. Such pumps, however, are of the vane type and result in a considerable amount of damage to the fish.
Vane type pumps are also used in the pumping of coal, slurry and the like. Such pumps, while effective in moving the slurry, are subject to high wear and rapid deterioration. They are also subject to clogging.
It is therefore desirable that a pump be available which is capable of rapidly and effectively conveying fragile articles by means of a fluid medium over a reasonable distance.